FIX: remove a spurious check in get_cast_transfer_function

njsmith · certik · commit d930c8827f2f · 2012-12-28T13:15:14.000-08:00
At least, I hope it's spurious. Certainly it's creating a spurious error message, is unexpected by callers (one of whom specifically makes the *opposite* check before calling get_cast_transfer_function), and even if it is a useful check for some reason I can't see, it certainly doesn't belong in this function (which is otherwise just taking care of byte-swapping and alignment issues and doesn't know anything about dtypes). And worst case, we'll have turned an exception into a crash; even if I'm wrong, this shouldn't cause any code to go from working to not working, just from broken to slightly-more-broken. Test and original diagnosis by @cgohlke. Fixes gh-2798.
diff --git a/numpy/core/src/multiarray/dtype_transfer.c b/numpy/core/src/multiarray/dtype_transfer.c
@@ -1475,14 +1475,6 @@ get_cast_transfer_function(int aligned,
     npy_intp src_itemsize = src_dtype->elsize,
             dst_itemsize = dst_dtype->elsize;
 
-    if (src_dtype->type_num == dst_dtype->type_num &&
-            src_dtype->type_num != NPY_DATETIME &&
-            src_dtype->type_num != NPY_TIMEDELTA) {
-        PyErr_SetString(PyExc_ValueError,
-                "low level cast function is for unequal type numbers");
-        return NPY_FAIL;
-    }
-
     if (get_nbo_cast_transfer_function(aligned,
                             src_stride, dst_stride,
                             src_dtype, dst_dtype,
diff --git a/numpy/core/tests/test_dtype.py b/numpy/core/tests/test_dtype.py
@@ -443,6 +443,9 @@ def test_dtype_str_with_long_in_shape(self):
         # Pull request #376
         dt = np.dtype('(1L,)i4')
 
+    def test_base_dtype_with_object_type(self):
+        # Issue gh-2798
+        a = np.array(['a'], dtype="O").astype(("O", [("name", "O")]))
 
 class TestDtypeAttributeDeletion(object):
 
